1. Field of the Invention
The present invention relates generally to jacks for jacking up cars, and more particularly, to a ratchet-based adaptor assembly for transitional connection between a jack and a wheel replacement wrench.
2. Description of the Related Art
Referring to FIG. 6, a conventional jack 70 for jacking up a car is comprised of a linkage 72, a screw rod 71 pivotally mounted through the linkage 72, and a rotatable joint 73 connected with the screw rod 71. The rotatable joint 73 includes two ears 74 extending outwards and respectively having a through hole 75 and a slot 76.
During operation of the jack 70, the user usually inserts a screwdriver 79 into the through hole 75 and the slot 76 and then manually rotate the screwdriver to drive the rotatable joint 73 to rotate together with the screw rod 71 so as to extend/retract the jack 70, thereby jacking up/down the car.
However, in the beginning, the jack 70 is low in elevation, so that the user would easily carelessly have the screwdriver 79 or the hand to rub the ground, interfering with operation of the jack 70 or even causing injury. In addition, since the moment of the force of the screwdriver for operating the jack 70 is little, operation of the jack 70 would be laborsome for users having little strength. Further, since the jack is low in elevation, it is hard to use a long hand tool of great moment of force upon the jack 70. Even if it is necessary to use the long hand tool of great moment of force, the user can only rotate the long hand tool inserted into one side of the jack 70 through a predetermined angle before having to remove the tool from the jack 70 and then insert the tool into the other side of the jack 70, to rotate the tool through a predetermined angle again, repeating the aforesaid steps for many times in an inconvenient manner.